Undercarriage for a rocking chair

ABSTRACT

1,138,328. Rocking chairs. AMERICAN METAL PRODUCTS CO. 6 Sept., 1966, No. 39692/66. Heading A4J. In a chair rocking mechanism, the rocking pivots 16 are positioned towards the rear of plate members 8 and 14, which they interconnect, and the rocking action is controlled by springs 29, which are effective both in tension and compression. A further compression spring 32 is adjustable by means of a wing-nut 34, to vary the resistance to rocking. The plates are carried on a ball-race 9 for swivelling about the axis of vertical pivot 10.

Augs 9 H. s. HUNT ETAL. 3,263,955

' UNDERCARRIAGE FOR A ROCKING CHAIR @rigiamai Filadi Sent. 1'22; 3360 :2 Shee2:s-Sheet l INVENTORS HOWARD s. HUNT ROY F. MMAHAN,JR.

ATTORNEY g @956 H. s. HUNT ETAL 3,

UNDERCARRIAGE FOR A ROCKING CHAIR 2 Sheetsfiheet 2 Original Filed SQDL 229 1960 HOWARD 5. HUNT ROY F. MMAHAN,JR.

game/1d,, bi m I ATTORNEY United States Patent 3,263,955 UNDERCARRIAGE FOR A ROCKING CHAIR Howard S. Hunt, Louisville, and Roy F. McMahan, In, Harrods Creek, Ky, assignors, by mesne assignments, to American Metal Products Company, Detroit, Mich., a corporation of Michigan Continuation of application Ser. No. 379,431, June 22, 1964, which is a continuation of application Ser. No. 282,188, Apr. 22, 1963, which is a continuation of application Ser. No. 58,6tl8, Sept. 22, 1960. This application Sept. 30, 1965, Ser. No. 491,783

19 Claims. (Cl. 248385) This application is a continuation of our application S.N. 379,431, filed June 22, 1964, now abandoned, which is a continuation of our now abandoned application S.N. 282,188, filed April 22, 1963, which is a continuation of our now abandoned application S.N. 58,608, filed September 22, 1960.

Rocking chairs of various types have heretofore been proposed. These types include the spring-supported, rocker-supported and pivot-supported types. The pivotsupported type normally comprises: (1) a base member; (2) a horizontal rocker member or plate spaced upwardly from the base member; (3) means mounting the rocker member on the base member for relative forward-backward rocking movement about a transversely extending horizontal rocking axis which is located in a vertical plane passing transversely through the center of the rocker member; and (4) front and rear compression springs vertically interposed between the rocker member and the base member on the front and rear sides of said axis to cushion the rocking movement in both directions by compression.

So far as we know, a commercially satisfactory rocking chair of the foregoing pivot-supported type has not heretofore been achieved. It has been our experience that when the undercarriage is made vertically compact, the vertical spacing of the rocker plate from the base is too small to perm-it a satisfactory degree or amout of rocking action. On the other hand, when this spacing was increased to the degree necessary to get a satisfactory amount of rocking action, we were unable to provide the somewhat bulky result with a satisfactory spring arrangement.

The principal objects of our invention are: to provide a compact and commercially satisfactory rocking chair undercarriage of the pivot su'pported type, which is of a simple compact design providing a highly satisfactory degree of rocking movement; to provide one which may be easily and inexpensively manufactured; and to provide one which may be easily and quickly incorporated in a rocking chair and which, when incorporated in a rocking chair, provides that chair with a soft, relatively free, yieldable rocking motion in both directions from a neutral position, and renders it useful as a rocker for children and for adults over a wide range of weights.

Another important object of the present invention is to provide an undercarriage with a simple adjustable mechanism which renders the chair useful as a rocker for adults of a wide range of heavy weights.

The principal objects of our invention are achieved by using a rearwardly offset pivot in combination with double action front springs. For example, where the undercarriage is vertically compact so that the vertical spacing between the rocker member and the base member is too small to provide a satisfactory amount of rocking action about a centrally disposed pivot, we have found: (1) that the amount of rocking action can be increased by offsetting the pivot axis rearwardly from the vertical center plane of the rocker member; and (2) that, by properly correlating the degree of offset with the amount of vertical spacing, one can increase the amount of rocking action to a satisfactory level. Furthermore, when the undercarriage is incorporated in a rocking chair, the rearice ward offset of the pivot axis not only reduces the possibility of that chair turning over backwardly but also facilitates the use of double action front springs, which provide a soft relatively-free yieldable rocking motion for children and adults over a wide range of weight. By double action springs, we mean springs which, on one side of a neutral position, act in tension and, on the opposite side of that neutral position, act in compression. Thus, double action front springs operate, at the front end of the undercarriage, (a) to cushion at least the extreme portion of the forward rocking movement by compression and (b) to cushion at least the extreme portion of the backward rocking movement by tension.

More specifically, objects of this invention may be attained by a device including a rocker member with front and rear ends, a base member, means mounting the rocker member on the base member for identicallyrepetitive rocking movement of both ends of the rocker member through respective paths during each oscillation forwardly and rearwardly through a neutral position about a rearwardly offset horizontal axis, and front spring means interconnecting the rocker member and the base member adjacent the front ends thereof to resist by tension at least the extreme portion of the rocking movement of the rocker member in one direction (backward) from the neutral position and to resist by compression at least the extreme portion of the rocking movement of the rocker member in the opposite direction (forward) from the neutral position.

Other objects of this invention are achieved, in accordance with our invention, by using an adjustable rear compress-ion spring. The rearward offset of the pivot axis reduces the vertical travel or the amount of rocking movement of the rear end of the rocker member and thus facilitates the use thereat of a short compression spring to cushion at least a portion of the backward rocking movement by compression. A short rear compression spring cooperates with the front spring means not only to render the chair useful for adults over a wide range of heavy weights but also to maintain a soft relatively-free yieldable rocking motion. The rear spring adjustment feature enables its resistance to further compression to be increased to still higher levels and thereby provide a corresponding increase in the range of heavy weights which can be accommodated by a rocking chair equipped with this undercarriage.

An embodiment of our invention is illustrated in the accompanying drawings wherein:

FIGURE 1 is a side elevational view of a swiveled rocking chair constructed in accordance with our invention;

FIGURE 2 is a top plan view of the undercarriage of the chair shown in FIGURE 1;

FIGURE 3 is an enlarged .top plan view of FIGURE 2 with the legs of the base broken away;

FIGURE 4 is an elevational view of the right side of the undercarriage of FIGURE 3;

FIGURE 5 is a vertical section taken on line 5-5 0f FIGURE 3; and

FIGURE 6 is an enlarged section taken on line 66 of FIGURE 4.

Our invention, which is illustrated as applied to swiveled rocking chairs, is suited for use also with non-swiveled chairs. The swiveled rocking chair shown in FIGURE 1 conventionally includes a rigid seat-backrest unit 1 having an arm rest 2. This conventional unit is supported by an integrated metal undercarriage 3 which is constructed in accordance with our invention.

UNDERCARRIAGE The undercarriage 3 supports the unit 1 for rotational movement about a central vertical axis and for rocking movement about a rearwardly offset horizontal axis. The undercarriage includes: a support; a swivel mounted on the support for rotation about a vertical axis; a rocker member or plate; means mounting the rocker member on the swivel for rotation therewith and for rocking movement relative thereto; and spring means controlling the rocking movement of said rocker member.

Support The support comprises a radial series of outwardly declined legs 4, the inner ends of which are rigidly secured, by rivets 5, to a rigid center plate 6.

Swivel The swivel, which is mounted on the support, conventionally includes: the center plate 6 of the support as the lower stationary plate of the swivel; an upper or top rotary base member or swivel plate 8; means providing plate 6 and base member 8 with corresponding annular ball bearing races containing ball bearings 9 which space the plate 6 and base member 8 apart and provide a rolling bearing means between them; and means operatively connecting the plate 6 and base member 8 together for relative rotation about a fixed vertical axis.

The center plate 6 and the base member 8 are connected by means including: a center bolt 10 having a head at its upper end abutting the top of the base member 8, an adjacent square shank portion seating in a corresponding square hole in the base member 8, and a threaded lower, or bottom end portion; and a small thrust bearing 11 threaded to the lower end of the bolt 10 and seating against the bottom face of the center plate 6. This thrust bearing provides an anti-friction bearing means between the bolt and the plate 6 and functions cooperatively with the bolt to press the base member 8 and plate 6 together with a clamping force, which may be adjusted by adjusting the position of the thrust bearing 11 on the threaded end of bolt 10.

Rocker member The rocker member 14 is spaced vertically a desired distance from the base member 8. This spacing should be minimized to promote compactness. The preferred spacing is, therefore, too small to permit the requisite degree of relative rocking movement when a centrally disposed rocker member pivot axis is used. The rocker member also contains suitable apertures to receive the screws used in securing it to the rigid seat-backrest unit 1.

Pivotal mounting means The rocker member 14 is pivotally mounted on the base member 8 for rotation with the base member 8 of the swivel and for forward-backward rocking movement relative to the base member 8 of the swivel. To facilitate the vertical spacing of the rocker member from and its pivotal mounting on the base member 8, the side margins of each of the members 8 and 14 are bent toward the other member to form two pairs of adjacent side flanges, one pair of adjacent flanges at each side of the undercarriage, each pair consisting of one upstanding and one depending flange which are close enough to each other for pivotal interconnection.

Accordingly, the side margins of the base member 8 are bent upwardly to form upstanding side flanges 13 while the corresponding side margins of the rocker member 14 are bent downwardly to form depending side flanges 15. In other words, both members are channel-shaped and the channel-shaped rocker member 14 is inverted over the channel-shaped base member 8 so that their adjacent flanges may be pivoted together.

As illustrated, the respective flanges 13 and 15 on each I side of the member 8 and 14 are pivoted together, on a rearwardly offset axis, by rivets 16. The rivets 16 are axially aligned with each other on the rearwardly oflset axis about which the rocker member 14 rocks. The rocker member 14 is mechanically constrained through the flanges 15 and rivets 16 for identically-repetitive rocking movement relative to the base member 8 so that each of the respective ends of the rocker member 14 moves about the rearwardly offset axis as defined by the rivets 16. It is to be understood, however, that various mechanically equivalent means may be utilized, other than the flanges 13 and 15 and rivets 16, to mount the rocker member 14 on the base member 8 so that both ends of the rocker member 14 move relative to the base member 8 through respective identically-repetitive paths during successive oscillations forwardly and rearwardly through the neutral position (shown in FIGURE 5 and more fully discussed hereinafter) about the rearwardly offset horizontal axis, which is defined in the illustrated embodiment by the rivets 16. The axis, as defined by the rivets 16 in the illustrated embodiment, is rearwardly offset, from the vertical center plane of the rocker member, a distance ranging from about 30% to about 40% of the distance between that plane and the rear end of the rocker member. It should be noted (in FIGURE 4) that the spacing between the two upright side flanges 13 equals the spacing between the two depending side flanges 15 so that when the two pairs of flanges are overlapped, both of the upper flanges 15 are offset in the same direction from their respective lower flanges 13. This arrangement allows both pairs of flanges 13 and 15 to be bent or shaped on the same die.

It is highly desirable that the rocking action of the chair be noiseless. A relatively noiseless action may be achieved by using nylon or some other suitable plastic material to insulate all stationary metal surfaces of the pivotal mounting from each adjacent relatively movable rubbing surface. This is accomplished in each pivotal mounting structure shown in FIGURE 6 by rigidly connecting the rivet 16 to one side flange while insulating the other side flange from the rivet and from the adjacent flange through the agency of a nylon bushing or sleeve and pair of nylon washers, one at each end of the bushing.

A rivet 16 of the shoulder type is particularly suited for use in providing a pivotal structure involving a rigid connection to one part or flange 15 and a movable insulated connection to the other part or flange 13. Such a rivet 16 comprises: a head; and a stem which is stepped intermediate its ends to provide a head end portion 17 of one diameter, extending axially from the head 16 and terminating in an annular shoulder 18, and a free end portion 19 of relatively reduced diameter, extending axially from the annular shoulder 18 to the free end of the stem which contains an end opening 20 to facilitate the conventional peening or rolling of the free end of the rivet to form a'securing bead or flange 21. With a shoulder rivet, the movable insulated connection to one flange 13 is made around the large head end portion 17 of the rivet while the rigid connection to the other flange 15 is made on the reduced free end portion 19 of the rivet, this particular flange being gripped or clamped rigidly between the annular shoulder 18 and the securing flange 21.

Accordingly, the movably connected side flanges 13 must be provided with a pivotal receiving opening large enough to accommodate the head end portion 17 of therivet and the means for insulating that portion from the respective flanges while the rigidly connected side flanges 15 must be provided with a pivotal opening dimensioned to fit the slender free end portion 19 of the rivet very snugly. Both of these side flanges preferably have their pivotal openings axially flanged to provide a larger and better bearing surface.

With the foregoing in mind, each pivotal mounting may be effected by threading the parts together in the appropriate order and then riveting the appropriate side flange on the slender or reduced free end portion of the rivet. The threading operation for the pivotal connection shown in FIGURE 6 and at the bottom of FIGURE 4 is performed by threading the rivet 16 successively through a nylon washer 23, a nylon sleeve or bushing 24 lining the large pivot opening of upright side flange 13, a nylon washer 25 and the small pivot opening in depending side flange 15. The movable and rigid connections of rivet 16 at the bottom of FIGURE 4 are reversed at the top of that figure but only because it is easier to peen the rivet on the outside of side flanges. A nylon sleeve liner 24 and nylon washer 25 may be rovided by a flanged bushing as shown rather than as separate parts.

Spring means In further accordance with our invention, the rocking movement of the upper rocker member 14 on the base member 8 is controlled by a spring means including: double acting front spring means located between and anchored to the front end portions of the rocker member 14 and the base member 8 and operative to resist or cushion by tension at least the extreme portion of the backward rocking movement of the rocker member 14 from the neutral position and to resist or cushion by compression at least the extreme portion of the forward rocking movement of the rocker member 14 from the neutral position. The double action front spring means interconnects the rocker member 14 and the base member 8 on the side opposite the transverse vertical plane passing through the mid-portion of the rocker member 14 from the transverse axis defined by the rivets 16. Preferably the spring means also includes: rear spring means located betweenthe rear end portions of the rocker member 14 and the base member 8 and freely separable from at least one of the members 8 and 14, said rear spring means being operative to resist at least the extreme portion of the backward rocking movement of the rocker member 14 by compression and being inoperative to resist the forward rocking movement of the rocker member 14; and means for adjusting the compression of the rear spring means. That is to say, the rear spring means is operatively disposed between the rocking member 14 and the base member 8 on the side opposite the transverse axis defined by the rivets 16 from the transverse vertical plane passing through the midportion of the rocker member 14 to cushion or resist a portion, or all, depending upon the adjustment, of the rearward rocking movement of the rocker member 14 from the neutral position.

Double acting front spring means The front spring means comprises a pair of integral double action normally open coil springs 29 connected between and rigidly or firmly anchored to the front edges of both the upper rocker member 14 and the base member 8. The anchorage of each spring 29 to each respective member is accomplished by inserting the front edge of the member between the last two spring coils, at one end of the spring, and bending a tongue 30, previously formed in the member during its manufacture, outwardly to abut the inside of the last spring coil and hold it against slipping out of its position on the member. This same type of anchorage is provided at both ends of both springs 29. The double anchorage renders the spring double acting.

The front springs 29 are selected so that, when relaxed or in equilibrium, they will maintain or hold the upper rocker member 14 substantially in the neutral position shown in full lines in FIGURE 5. When the upper rocker member 14 is rocked backward, as shown in dotted lines in FIGURE 5, its front edge rises and places the springs 29 in tension. The tension resistance of the springs progressively increases as the member 14 rocks backward.

6 member 14 will be at the extreme limits of its rocking movement in both directions.

Single acting rear spring means The rear spring means simply constitutes a single coil spring 32 placed between the rear end portions of the rocker member 14 and the base member 8, a short distance rearwardly of the common rocking axis provided by the rivets 16. In the preferred embodiment shown, the spring 32 is not anchored to the upper rocker member 14, but is separable from it, so that when the rocker member 14 is rocked forward from its neutral position, its rear end tends to (but does not necessarily) lift off the spring 32, rather than placing it in tension. Hence, the spring 32 offers no resistance to forward rocking movement of the upper rocker member 14, but rather resists or cushions some portion of the rearward rocking movement of rocker member 14. Also, the rear spring means is disposed closer to the transverse axis defined by the rivets 16 than the front spring means.

Rear spring adjustment means The rear spring adjustment means includes an adjusting member 34 which is located within the rear end portion of the box chamber and is interposed between spring 32 and base member 8 where it is accessible for adjustment through the rear access opening of the box. The bottom of the rear spring 32 sits in a cup-shaped nut 34 which is threaded on a vertical stud 35 projecting upwardly from the base member 8, adjacent its rear end. Screwing the nut 34 upwardly and downwardly simply raises and lowers the elevation of the rear spring as a whole and thereby increases and decreases, or selectively changes, the resistance offered by the rear spring 32 to backward rocking movement of the upper rocker member 14. It also will tend to change the neutral position of the upper rocker member 14 slightly. Normally, the nut 34 is screwed upwardly at least far enough to hold the top of the rear spring 32 snugly (at least lightly) against the rocker member 14 in all of its positions but the nut 34 may also be screwed downwardly far enough so that the top of the rear spring 32 is in spaced relation to the rocker member 14 so that the rear spring 32 does not resist the initial rearward rocking movement of the rocker member 14 from the neutral position. That is to say, the rear spring 32 resists or cushions at least a portion of the rearward rocking movement, the portion of rearward rocking movement resisted by the rear spring 32 depending upon the length of the spring 32 and the adjustment of the nut 34. The front spring means normally holds the rocker member 14 in the neutral position illustrated in solid lines in FIGURE 5. When the rear spring means is adjusted so that the rear spring 32 applies no force to the rocker member 14 in the neutral position, the front spring means (springs 29) is neither in compression nor tension in the neutral position so that the front spring means re sists by compression rocking movement of the rocker member 14 on a first side (forward) of the neutral position and resists by tension rocking movement of the rocker member 14 on the second side (rearward) of the neutral position. And, regardless of the adjustment of the rear spring means, the front spring means resists by compression at least the extreme portion of forward rocking movement of the rocker member 14 and resists by tension at least the extreme rearward rocking movement of the rocker member 14. Likewise, the rear spring means resists at least the extreme rearward rocking movement of the rocker member 14 regardless of the adjustment thereof.

Obviously also one may vary the number of springs used, e.g., using one single or integral double action normally-open coil spring 29 at the front instead of the two shown or two single action springs at the rear instead of the one shown. Furthermore, in the smaller chairs made to accommodate lighter weights, the single action spring at the rear may be entirely omitted.

7 SUMMARY It will be appreciated that the base member 8, the rocker member 14 and the elements associated therewith provide a rocker assembly for the undercarriage of rocking chairs and the like comprising: a rocker box having front and rear ends, a vertical center plane passing transvesely through the box substantially midway between its ends, a horizontal base member 8, a horizontal rocker member 14 cooperating with the base member 8 to form a box chamber extending from one end of the box to the other and an access opening for the rear end portion of the box chamber, and means 13, 15 and 16 at opposite sides of the box chamber pivotally mounting the rocker member 14 on the base member 8 for relative forwardbackward rocking movement about a transversely extending horizontal rocking axis, corresponding to the transverse center of pivot 16, which axis is spaced a substantial distance forwardly from the rear end of the box and offset a substantial distance rearwardly from the vertical center plane; double action spring means 29 located at the front end portion of said box chamber where it is not only spaced forwardly from said vertical center plane a distance substantially greater than the offset spacing of said rocking axis from the plane, and vertically arranged between members 8 and 14, but is also anchored to both members 8 and 14 so as to be operative to resist or cushion at least the extreme portion of the forward rocking movement by compression and at least the extreme portion of the backward rocking movement by tension.

In its broadest aspects, therefore, the instant invention provides a device for a rocking chair and includes a base member, a rocker member having first and second ends, means operatively interconnecting the base member and the rocker member for allowing identically-repetitive oscillatory rocking movement of the rocker member relative to the base member on either side of a neutral position so that the first and second ends of the rocker member respectively move about a transverse axis disposed between a plane passing transversely through the midportion of the rocker member and the first end of the rocker member, and spring means interconnecting the rocker member and the base member on the side opposite the plane passing transversely through the mid-portion of the rocker member from the transverse axis for normally holding the rocker member in the neutral position and for resisting by compression rocking movement of the rocker member on one side of the neutral position and for resisting by tension rocking movement of the rocker member on the opposite side of the neutral position.

While this arrangement uses only one set of springs, it has the advantage of cushioning or resisting movement in both directions. It has another important advantage in that its pivotal axis is located suificiently rearward as to render it extremely difficult to rock the chair backwardly to a dangerous degree. While some of the advantages which it possesses from a manufacturing standpoint are believed to be obvious, one particular advantage which is not so obvious resides in its flexibility. This design is flexible because it is particularly suited for use by children and adults in the lighter weight classes and it can be readily suited for use by adults of the heavier weight classes.

To suit it for use by adults of the heavier Weight classes, it is only necessary to add the single action spring means 32. This means is located on the rear side of the rocking axis where it is operative to resist or cushion at least the extreme portion of the backward rocking movement by compression but is inoperative to resist the forward rocking movement by tension. Since the transverse pivot axis is rearwardly offset, the single action spring means is located much closer to the transverse pivot axis than is the double acting front spring means. As a result, the short leverage extending from that axis to the rear spring renders it doubly effective in preventing backward rocking movement to a dangerous degree.

Furthermore, it is possible to extend comfortable and safe use of the invention by adults over a wide range of weights by providing adjustment means for adjusting the maximum compression of the rear single action spring means.

We have gotten excellent results with a rocker box constructed in accordance with the embodiment of the invention illustrated in FIGURES 1 through 6, which comprises: top and bottom members, each approximately 7%" long from front to rear and 7%" wide and each having its pivotal axis offset 1%" rearwardly from a vertical plane passing transversely through the center of these members and spaced 2 /2" forwardly from the rear end of the members and 1.0" downwardly from the ceiling of the rocker member and upwardly from the floor of the base member, the base member having a vertical axis of swivel rotation which is spaced 1%" forwardly from the pivotal axis, 3%" from the rear end of the base member and 4" from the front thereof. Accordingly, by the term vertical center plane of the rocker box (or of the rocker member), we mean a vertical plane passing transversely through the mid-portion of the rocker box (or of the rocker member) so as to be in the vicinity of one or the other or both of the two vertical planes which pass transversely through the mid portion of the box, one going through the center of both members (or of the rocker member) and the other going through the axis of swivel rotation.

The invention has been described in an illustrative manner and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation.

Obviously, many modifications and variations of the present invention are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described.

Having described our invention, we claim:

1. A rocker assembly for the undercarriage of rocking chairs and the like, comprising:

a base member;

a horizontal rocker member having first and second ends and positioned over and spaced upwardly from said base member;

means mounting said rocker member on said base member for relative forward-backward rocking movement of both of said first and second ends of said rocker member about a transversely-extending horizontal rocking axis,

which is offset a substantial distance rearwardly from a vertical center plane passing transversely through the mid-portion of said rocker member; and

double action spring means other than said first-named means located on the front side of said rocking axis, vertically arranged between the rocker member and the base member, and secured to both so as to be operative to cushion at least the extreme portion of the forward rocking movement by compression and of the backward rocking movement by tension.

2. The rocker assembly of claim 1 wherein: said double action spring means comprises at least one normally open ended coil spring.

3. The rocker assembly of claim 1 including:

single action spring means located on the rear side of said rocking axis,

vertically arranged between the rocker member and the base member, and

secured to one of said rocker-member and base-member parts to resist at least the extreme portion of the backward rocking movement by compression without cushioning the forward rocking movement.

4. The rocker assembly of claim 3 including:

means for adjusting the resistance of said single action spring means to compression,

said means including an adjusting member which is located between said single action spring means and one of said rocker-member and basemember parts and which is accessible for adjustment at the rear end portion of the space between said parts.

5. A rocker assembly for the undercarriage of rocking chairs and the like, comprising:

a base member;

a horizontal rocker member having first and second ends and positioned over and spaced upwardly from said base member;

means mounting said rocker member on said base member "for relative forward-backward rocking movement of both of said first and second ends of said rocker member about a fixed transversely-extending horizontal rocking axis,

which is offset a substantial distance rearwardly from a vertical center plane passing transversely through the mid-portion of said rocker member; and

double action spring means located on the front side of said rocking axis, vertically arranged between the rocker member and the base member, and

secured to both so as to be operative to cushion at least the extreme portion of the forward rocking movement by compression and of the backward rocking movement by tension.

6. An integrated metal undercarriage of the type suited for use in mounting the rocker member of a rocking chair on the base member thereof for rocking movement, comprising:

' a metal base member having front and rear ends;

a metal rocker member having front and rear ends, said rocker member being positioned over and spaced upwardly from said base member;

means mounting said rocker member on said base member and mechanically-constraining said rocker member for identically-repetitive rocking movement relative to said base member forwardly and rearwardly through a neutral position so that said front and rear ends of said rocker member each respectively move about a transversely-extending horizontal rocking axis which, in said neutral position, is offset from a vertical center plane passing transversely through the mid-portion of said rocker member a rearward distance suflicient to provide a substantial rocking movement in both directions from said neutral position and an integral double action spring located on the front side of said rocking axis, and vertically arranged between the rocker member and the base meber, and

rigidly secured at its upper end to the front end portion of the rocker member and at its lower end to the underlying front end portion of the base member so as to be operative to hold the rocker member yieldably in said neutral position, and

to resist at least the extreme portions of the rocking movement in the forward direction by compression and in the rearward direction by tension.

7. The undercarriage of claim 6 wherein: said double action spring is in the form of a normally-open coil spring.

8. The undercarriage of claim 6 wherein: said rocking axis is fixed.

9. A rocker assembly for the undercarriage of rocking chairs and the like comprising:

a base member,

a rocker member having first and second ends,

means operatively interconnecting said base member and said rocker member for allowing identically repeti- 10 tive oscillatory rocking movement of said rocker member relative to said base member on either side of a neutral position so that said first and second ends of said rocker member respectively move about a transverse axis disposed between a plane passing transversely through the mid-portion of said rocker member and said first end of said rocker member, and spring means interconnecting said rocker member and said base member on the side opposite said plane from said transverse axis for normally holding said rocker member in said neutral position and for resisting by compression rocking movement of said rocking member on a first side of said neutral position and for resisting by tension rocking movement of said rocking member on the second side of said neutral position.

10. The assembly as set forth in claim 9 including second spring means operatively disposed between said rocking member and said base member on the side opposite said axis from said plane to resist at least the extreme portion of said rocking movement of said rocker member on said second side of said neutral position.

11. The assembly as set forth in claim 10 including an adjustment means operatively connected to said second spring means for selectively changing the resistance offered by said second spring means to said rocking movement on said second side of said neutral position.

12. The assembly as set forth in claim 10 wherein said second spring means is disposed nearer to said transverse axis than said first-mentioned spring means.

13. An undercarriage for a swiveled rocking chair comprising;

a support,

a base member operatively connected to said support for rotation relative thereto about a vertical axis,

a rocker member having first and second ends,

means operatively interconnecting said rocker member and said base member so that said rocker member rotates about said vertical axis with said base member and for allowing identically-repetitive oscillatory rocking movement of said rocker member relative to said base member on either side of a neutral position so that said first and second ends of said rocker member respectively move about a transversely extending horizontal axis disposed between a plane passing transversely through the mid-portion of said rocker member and said first end of said rocker member, and

spring means interconnecting said rocker member and said base member on the side opposite said plane from said transverse axis for normally holding said rocker member in said neutral position and for resisting by compression rocking movement of said rocker member on a first side of said neutral position and for resisting by tension rocking movement of said rocker member on the second side of said neutral position.

14. A rocker assembly for the undercarriage of rocking chairs and the like comprising:

a base member;

a rocker member having first and second ends;

means operatively interconnecting said base member and said rocker member for allowing identically repetitive oscillatory rocking movement of said rocker member relative to said base member on either side of a neutral position so that said first and second ends of said rocker member respectively move about a transverse axis disposed between said first end of said rocker member and a plane passing transversely through the mid-portion of said rocker member; and

spring means operatively connected between said base member and rocker member for resisting rocking movement of said rocking member from said neutral position.

1 1 r 15. A rocker assembly for the undercarriage of rocking chairs and the like comprising:

a base member having first and second ends, a rocker member, means operatively interconnecting said base member and said rocker member for allowing identically repetitive oscillatory rocking movement of said rocker member relative to said base member on either side of a neutral position so that said first and second ends of said rocker member respectively move about a transverse axis disposed between said first end of said base member and a plane passing transversely through the mid-portion of said base member, and spring means operatively connected between said base member and rocker member for resisting rocking movement of said rocking member from said neutral position. 16. A rocker assembly for the undercarriage of rocking chairs and the like comprising:

a base member, a rocker member having first and second ends, means operatively interconnecting said base member and said rocker member for allowing identically repetitive oscillatory rocking movement of said rocker member relative to said base member on either side of a neutral position so that said first and second ends of said rocker member respectively move about a transverse axis which is always disposed between said first end of said rocker member and a plane passing transversely through the mid-portion of said rocker member, and r spring means operatively connected between said base member and rocker member for resisting rocking movement of said rocking member from said neutral position. v I 17. A rocker assembly for the undercarriage of rocking chairs and the like comprising:

a base member having first and second ends,

a rocker member having first and second ends,

means operatively interconnecting said base member and said rocker member for allowing identically repetitive oscillatory rocking movement of said rocker member relative to said base member on either side of a neutral position so that said first and second ends of said rocker member respectively move about 12 a transverse axis disposed between said first end of one of said members and a plane passing transversely through the midportion of one of said members, and spring means operatively connected between said base member and rocker member for resisting rocking movement of said rocking member from said neutral position. 18. A rocker assembly for the undercarriage of rocking chairs and the like comprising:

a base member, a rocker member having first and second ends, means operatively interconnecting said base member and said rocker member for allowing identically repetitive oscillatory rocking movement of said rocker member relative to said base member to a greater degree on one side of a neutral position than the other, and spring means operatively connected between said base member and rocker member for resisting rocking movement of said rocking member from said neutral position. 19. The rocker assembly defined in claim 17 wherein said axis is fixed relative to said base member and said rocker member.

References Cited by the Examiner UNITED STATES PATENTS 582,799 5/1897- Randow 248204 593,068 11/1897 Hulse 297326 X 1,155,893 10/1915 Crippen 248384 1,437,848 12/1922 Kisor et al 248385 1,770,955 7/1930 Storm 24435 2,270,430 1/1942 Fox 248396 2,339,953 1/1944 Schlorman 297326 2,409,826 10/1946 Berstein 248388 2,625,983 l/1953 Slyter et a1 297-363 2,729,273 1/1956 Hamilton et a1. 248379 2,746,518 5/1956 Schneider 297-302 2,768,674 10/1956 Phenix 297-300 2,913,284 11/1959 Zankl 308-15 2,916,084 12/1959 Bottcmiller 297326 3,070,342 12/1962 Babbitt 248376 CLAUDE A. LE ROY, Primary Examiner. 

1. A ROCKER ASSEMBLY FOR THE UNDERCARRIAGE OF ROCKING CHAIRS AND THE LIKE, COMPRISING: A BASE MEMBER; A HORIZONTAL ROCKER MEMBER HAVING FIRST AND SECOND ENDS AND POSITIONED OVER AND SPACED UPWARDLY FROM SAID BASE MEMBER; MEANS MOUNTING SAID ROCKER MEMBER ON SAID BASE MEMBER FOR RELATIVE FORWARD-BACKWARD ROCKING MOVEMENT OF BOTH OF SAID FIRST AND SECOND ENDS OF SAID ROCKER MEMBER ABOUT A TRANSVERSELY-EXTENDING HORIZONTAL ROCKING AXIS, WHICH IS OFFSET A SUBSTANTIAL DISTANCE REARWARDLY FROM A VERTICAL CENTER PLANE PASSING TRANSVERSELY THROUGH THE MID-PORTION OF SAID ROCKER MEMBER; AND DOUBLE ACTION SPRING MEANS OTHER THAN SAID FIRST-NAMED MEANS LOCATED ON THE FRONT SIDE OF SAID ROCKING AXIS, VERTICALLY ARRANGED BETWEEN THE ROCKER MEMBER AND THE BASE MEMBER, AND SECURED TO BOTH SO AS TO BE OPERATIVE TO CUSHION AT LEAST THE EXTREME PORTION OF THE FORWARD ROCKING MOVEMENT BY COMPRESSION AND OF THE BACKWARD ROCKING MOVEMENT BY TENSION. 